Physical and cognitive rest are recommended as the cornerstone of treatment for concussion, largely based on expert opinion.1- 3 However, it is unclear whether physical and cognitive rest aid recovery in youths with a concussion.4 In fact, a 2015 study suggests prolonged rest may correlate with more symptoms.4 Also unknown is the extent to which pediatric patients adhere to recommendations for physical and cognitive rest.5 We aimed to (1) determine the feasibility of ecologic momentary assessment following youth concussion, (2) gather real-time reports of cognitive and physical activity, and (3) compare objective measures with real-time reported symptoms among youths during recovery after concussion.